A large blue shift of electroluminescence (EL) was achieved from oxidizedn-type porous silicon (PS) in a persulphate solution under cathodic polarization. The two-peak phenomenon observed in the EL spectrum suggests that there are two types of luminescent centers located in the nanoscale silicon particles and at the surface of the oxidized PS layer, respectively. It is found that only the low-energy peak having luminescent centers in nanoscale silicon particles can be tuned by voltage, supporting the quantum confinement model. ©1998 American Institute of Physics.